Philips LDL 8740 videotape 1" - Videokarma.org TV - Video

firenzeprima · #1 07-14-2011, 03:13 PM

hello. can anyone help me to find the schematic or service manual of this device. is identical to Siemens Sirecord XH or Grundig 310 Bk
Thank!!!

firenzeprima · #2 06-26-2013, 10:56 AM

hello anyone knows the cause of the flashing of the video record button in standby mode? just turn on the VTR the video record red lamp flashes for a moment, then turned OFF, and then start flashing again. In play mode you do not see any picture and the lamp flashes. Surely it means there is something wrong.
Can you help me?

Chip Chester · #3 06-26-2013, 11:14 AM

Don't know this particular machine, of course.
In other 1" machines, flashing transport controls usually indicate either absence of some critical signal -- video in, reference black, or possibly separate sync, etc. on a machine of that vintage. Could be NTSC/PAL/SECAM issue too, depending on its system standard.

Secondarily, it could mean trouble in the related system -- although I've not seen that on a 1" machine. So, flashing FF would mean some sort of FF system issue -- stuck brake release, bad motor fault -- something like that. But that's way, way more of a guess than answer 1.

Are you sure tape is threaded correctly? Oxide in/out on the reel was a variable back then, I believe. Wiki might know...

Chip

Electronic M · #4 06-26-2013, 01:32 PM

Might want to consult Labguy on his website Labguy's world. He is an expert on early VTRs.

firenzeprima · #5 06-27-2013, 02:12 PM

thanks for your answers. The tape is positioned correctly, the video display shows something but it looks like an image without sync. VTR is the type black and White standard CCIR. I guess its something related to the speed of the rotating drum, but you can not figure out what the cause is. I replaced the motor belt drum heads and verified the video heads.

firenzeprima · #6 06-28-2013, 05:30 PM

too Labguy's world are looking for service manual

Chip Chester · #7 06-28-2013, 09:59 PM

Can you post a clear, big photo of the connector panel on the machine?
Also, the front-panel switches?

Sometimes it's as easy as Sync: Internal/External.
(But then again, sometimes it's: the internal sync circuit is bad...)

Chip

firenzeprima · #8 07-02-2013, 03:20 AM

on the connector panel is that of the external synchronization, but on the control panel there is no switch. The changeover must be automatic. the defect must be some internal card but no scheme is almost impossible'm trying to check but it is not simple

Dave A · #9 07-02-2013, 07:07 PM

I would start with a PS recap and then see where your are.

firenzeprima · #10 07-03-2013, 06:58 AM

just done month ago, .... the head are ok, the rubber belt replaced ....

firenzeprima · #11 07-11-2013, 06:07 AM

http://youtu.be/lsdCSNDwDpE this is the link for see the trouble

Chip Chester · #12 07-11-2013, 10:38 AM

Nice clean machine.
So to be clear, the issues are:
1. Apparent head drum speed
2. Does flashing red record light mean anything?
3. Video in E-E (straight thru electronics-to-electronics) shows signal, but it's bad, like no sync or wrong standard.
4. Doesn't play back. (?)

So, starting with 4 first: are you playing back a known-good recording that works on that deck, and with the video system of the deck and monitor? (Don't just rely on a tape label for this info.)

The reason I ask is that the tape sounds like it's been bulk-erased, with the woop-woop sound in FF/RW. I suppose those could be full-frequency audio sweep tests, too. So, what's on that tape?

Next, #1. I know that on an Ampex/Nagra portable 1" machine, it was sensitive to the head cleaner used. Since it had no on-board air compressor, the head cleaner had a (silicone?) lubricant mixed with it. Without that special head cleaner/lube, it would be off-speed for recording and playback.

2. Flashing record light. Have you tried to make a recording? Does it operate by just pushing the record button, or do you do play+record? Again, video system of deck and source signal come into play.

And... although I've not done much research, I've never heard of a monochrome 1" machine. Monochrome 1/2", sure. But not 1". If it is looking for a "pre-color" input or reference signal, those may be hard to come by. Maybe start with a BW video camera...

And also, there may be multiple video inputs on this thing. One via BNC (for instance) and another via camera multi-core cable. Same with reference signals. Any switches/connectors for that? Still would be interesting to see a photo of the connector panel...

3. Video input monitor. When you plug your test signal directly into the monitor, using the same cable as you use with the VTR, do you get an expected image? Does the monitor tell you the video system type when displayed? Using the same cable, plug into the deck while playing your tape. Same image as E-E image?

Chip

firenzeprima · #13 07-11-2013, 04:25 PM

the noise you hear was a video recording of a surveillance camera of a square eternal and the noise can not remember exactly what it was, I cleaned the video heads several times with solvent, I replaced all the ability, I tried to record a video with colored bars. I tried to synchronize with an external source, but nothing flash the video recording button is definitely going to say that something is wrong on the circuit of revolutions of the drum, in fact at the beginning then blinks for a moment and then power off. but no one has the service manuals, knows well the diagnostics. I can also show just what you see on a monitor

ppppenguin · #14 07-13-2013, 01:38 AM

Quote:

Originally Posted by Chip Chester

And... although I've not done much research, I've never heard of a monochrome 1" machine. Monochrome 1/2", sure. But not 1". If it is looking for a "pre-color" input or reference signal, those may be hard to come by. Maybe start with a BW video camera...

Plenty of monochrome 1" machines. All the earllier Ampex 5000/7000 series (these were precursors of C Format) and IVC 700/800 series. There were also a few Philips machines and perhaps others (Sony?) that I've not come across. Not many survivors, especially in working order. I'm trying to find a working Ampex 5000/7000 machine to recover some tapes made by the student TV club at Imperial College, London, in the 1970s.

If you don't have a known good pre-recorded tape it's going to be hard. First get the E-E working. This will get the entire signal path sorted except for the final stage that puts RF on to the tape and the first stage that gets it off the tape. Then try recording, you can use a scope to check that the drum servo (and capstan servo if there is one) are locking. From my own experience many years ago with Ampex 7003, these were machines that needed a fair bit of attention to keep them working well.

Trying to get an unknown machine to work without full service info will be very difficult. Somebody with past experience on this general sort of machine might succeed but it still won't be easy. You've got a mixture of old components, precision mechanics (belts are a weak point, as in audio tape recorders) and fragile heads.

Chip Chester · #15 07-13-2013, 08:16 AM

Ok, wasn't expecting 1" mono. Do you know what happens when you feed a monochrome 1" machine color bars? Does it record them as monochrome, or does it work at all? My thought was that if he's testing a mono machine with current color test signals, he might be testing the collision of systems rather than the performance of his machine... but I considered that unlikely because I wasn't aware of the proliferation of mono 1".

I also read Labguy's site, and he (or a commentor) mentioned modifying other 1" machines for increased resolution for medical purposes. One would wonder whether this might be the case with the OP's machine. If it's looking for a thousand-line input signal, that's not going to happen very easily.

Chip